Is Overlord of the Balemurk legal in Standard, Modern, and Commander?

Overlord of the Balemurk is legal in: Standard, Modern, Pioneer, Legacy, Vintage, Commander, Historic.

Overlord of the Balemurk

Q: What type of card is Overlord of the Balemurk?

Overlord of the Balemurk is an Enchantment Creature — Avatar Horror. Its oracle text reads: "Impending 5—{1}{B} (If you cast this spell for its impending cost, it enters with five time counters and isn't a creature until the last is removed. At the beginning of your end step, remove a time counter from it.) Whenever this permanent enters or attacks, mill four cards, then you may return a non-Avatar creature card or a planeswalker card from your graveyard to your hand."

Enchantment Creature — Avatar Horror

Impending 5— (If you cast this spell for its impending cost, it enters with five time counters and isn't a creature until the last is removed. At the beginning of your end step, remove a time counter from it.)

Whenever this permanent enters or attacks, mill four cards, then you may return a non-Avatar creature card or a planeswalker card from your graveyard to your hand.

Set Duskmourn: House of Horror

Rarity Mythic Rare

Mana Value 5

Artist Babs Webb

Collector # 113

Scryfall Gatherer